Step 1

Make cookies: Sift together flour and salt into a medium bowl; set aside. Put butter in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed until fluffy, about 2 minutes. Add sugar; mix until smooth. Mix in egg. Reduce speed to low. Add flour mixture; mix until just combined. Wrap dough in plastic, and refrigerate until firm, about 2 hours.

Step 2

Preheat oven to 350 degrees. Roll out dough on a lightly floured work surface to 1/8 inch thick. Cut into 1 1/2-inch rounds. Using a spatula, transfer rounds to baking sheets lined with parchment paper, spacing 1 inch apart.

Step 3

Bake cookies, rotating sheets halfway through, until edges are golden, about 12 minutes. Transfer to wire racks using a spatula; let cool completely.

Step 4

Make filling: Put butter in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed until smooth, about 3 minutes. Add sugar, salt, and chestnut cream; mix until smooth.

Step 5

Make glaze: Melt chocolate in a small pan over low heat, stirring constantly; set aside.

Step 6

Assemble cookies: Spread filling on bottom of half the cookies. Sandwich with remaining cookies. Repeat with remaining cookies and filling. Dip sandwiches a third of the way into the warm glaze; transfer to wire racks set over baking sheets. Refrigerate until set, about 15 minutes.